Display panel and a display apparatus including the same

ABSTRACT

A display panel is provided including a substrate including a display area comprising first pixels and a sensor area including second pixels and a transmission portion. A display element layer is disposed on the substrate, the display element layer comprising the first pixels electrically connected to a first thin film transistor and the second pixels electrically connected to a second thin film transistor. A conductive layer is disposed between the second thin film transistor and the substrate, the conductive layer having two or more steps at an edge thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

This non-provisional patent application is a continuation of U.S. patentapplication Ser. No. 16/752,093 filed on Jan. 24, 2020, which claimspriority under 35 U.S.C. § 119 to Korean Patent Application No,10-2019-0037958, filed on Apr. 1, 2019 in the Korean IntellectualProperty Office, the disclosures of which are incorporated by referenceherein in their entireties.

TECHNICAL FIELD

The present invention relates to a display panel and a display apparatusincluding the display panel.

DISCUSSION OF THE RELATED ART

Display apparatuses have been incorporated into various electronicdevices, such as smart phones, tablet PCs, etc. Since the thickness andweight of the display apparatuses have been reduced, the range of usesof the display apparatuses has increased.

Different methods of designing a shape of display apparatuses have beendeveloped and more functions have been incorporated into the displayapparatuses.

SUMMARY

According to an exemplary embodiment of the present invention, a displaypanel is provided including a substrate including a display areacomprising first pixels and a sensor area including second pixels and atransmission portion. A display element layer is disposed on thesubstrate, the display element layer comprising the first pixelselectrically connected to a first thin film transistor and the secondpixels electrically connected to a second thin film transistor. Aconductive layer is disposed between the second thin film transistor andthe substrate, the conductive layer having two or more steps at an edgethereof.

According to an exemplary embodiment of the present invention, thedisplay element layer further comprises a scan line extending in a firstdirection. The scan line provides a scan signal to the second pixels,and the conductive layer is electrically connected to the scan line viaa contact hole.

According to an exemplary embodiment of the present invention, thedisplay element layer further comprises a driving voltage line extendingin a second direction. The driving voltage line applies a drivingvoltage to the second pixels, and the conductive layer is electricallyconnected to the driving voltage line via a contact hole.

According to an exemplary embodiment of the present invention, theconductive layer has a thickness of 1500 Å or greater.

According to an exemplary embodiment of the present invention, one ofthe two or more steps in the conductive layer has a thickness less than800 Å.

According to an exemplary embodiment of the present invention, theconductive layer comprises a first conductive layer and a secondconductive layer on the first conductive layer. The first conductivelayer and the second conductive layer include different materials fromeach other.

According to an exemplary embodiment of the present invention, the firstconductive layer comprises a first conductive material and the secondconductive layer comprises a second conductive material having an etchrate greater than an etch rate of the first conductive material.

According to an exemplary embodiment of the present invention, a widthof the second conductive layer in a first direction is less than a widthof the first conductive layer.

According to an exemplary embodiment of the present invention, athickness of an edge of the conductive layer is less than a thickness ofa center portion of the conductive layer.

According to an exemplary embodiment of the present invention, thesensor area comprises an auxiliary pixel area and a transmission area.The auxiliary pixel area has at least one of the second pixels and thetransmission area comprising the transmission portion, and

the auxiliary pixel area and the transmission area are arranged in agrid shape.

According to an exemplary embodiment of the present invention, the atleast one second pixel comprises a pixel electrode, a common electrode,and an intermediate layer, the common electrode facing the pixelelectrode and the intermediate layer being arranged between the pixelelectrode and the common electrode, and

the common electrode comprises an opening corresponding to thetransmission area.

According to an exemplary embodiment of the present invention, an imageprovided on the sensor area has a resolution that is less than aresolution of an image provided on the display area.

According to an exemplary embodiment of the present invention, a displayapparatus is provided including a substrate. The substrate includes adisplay area including first pixels, and a sensor area including secondpixels and a transmission portion. A display element layer is disposedon the substrate, the display element layer comprising the first pixelselectrically connected to a first thin film transistor and the secondpixels electrically connected to a second thin film transistor. Aconductive layer is disposed between the second thin film transistor andthe substrate, the conductive layer having two or more steps, and acomponent arranged under the substrate in the sensor area.

According to an exemplary embodiment of the present invention, thecomponent comprises an electronic element for emitting or receivinglight.

According to an exemplary embodiment of the present invention, thedisplay element layer further comprises a scan line and a drivingvoltage line. The scan line extends in a first direction and provides ascan signal to the auxiliary pixels, and the driving voltage lineextends in a second direction that intersects with the first directionand applies a driving voltage to the second pixels. The conductive layeris electrically connected to the scan line or the driving voltage linevia a contact hole.

According to an exemplary embodiment of the present invention, theconductive layer has a thickness of 1500 Å or greater.

According to an exemplary embodiment of the present invention, the twoor more steps in the conductive layer each have a thickness less than800 Å.

According to an exemplary embodiment of the present invention, theconductive layer comprises a first conductive layer and a secondconductive layer on the first conductive layer. The first conductivelayer and the second conductive layer include different materials fromeach other.

According to an exemplary embodiment of the present invention, the firstconductive layer includes a first conductive material and the secondconductive layer includes a second conductive material having an etchrate greater than an etch rate of the first conductive material.

According to an exemplary embodiment of the present invention, an imageprovided on the sensor area has a resolution that is less than aresolution of an image provided on the display area.

According to an exemplary embodiment of the present invention, a displaypanel is provided including a substrate including a display area. Afirst pixel and a sensor area are disposed in the display area. Thesensor area includes a second pixel and a transmission portion. Asensing component overlaps the second pixel and the transmissionportion. A light blocking layer is disposed between the sensingcomponent and the second pixel.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features of the present invention will become moreapparent by describing in detail exemplary embodiments thereof withreference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a display apparatus according to anexemplary embodiment of the present invention;

FIG. 2 is a cross-sectional view of the display apparatus taken alongline A-A of FIG. 1 according to an exemplary embodiment of the presentinvention;

FIG. 3 is a plan view of a display panel according to an exemplaryembodiment of the present invention;

FIG. 4 is a plan view showing an enlarged view of a sensor area SA ofFIG. 3 according to an exemplary embodiment of the present invention;

FIG. 5 is an equivalent circuit diagram of a pixel according to anexemplary embodiment of the present invention;

FIG. 6 is an equivalent circuit diagram of a pixel according to anexemplary embodiment of the present invention;

FIG. 7 is a cross-sectional view of a display panel according to anexemplary embodiment of the present invention;

FIGS. 8, 9, 10 and 11 are cross-sectional views of display panelsaccording to exemplary embodiments of the present invention;

FIG. 12 is a cross-sectional view of a display panel according to anexemplary embodiment of the present invention;

FIGS. 13 and 14 are cross-sectional views of display panels according toexemplary embodiments of the present invention; and

FIG. 15 is a cross-sectional view of a display panel according to anexemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Exemplary embodiments of the present invention will now be describedwith reference to the accompanying drawings. The present invention may,however, be embodied in many different forms and should not be construedas being limited to the embodiments set forth herein. Like referencenumerals may refer to like elements throughout the detailed descriptionand drawings.

It will be understood that when a layer, region, or component isreferred to as being “formed on” another layer, region, or component, itcan be directly or indirectly formed on the other layer, region, orcomponent. For example, intervening layers, regions, or components maybe present.

Sizes of components in the drawings may be exaggerated for convenienceof explanation.

The x-axis, the y-axis and the z-axis are not limited to three axes ofthe rectangular coordinate system, and may be interpreted in a broadersense. For example, the x-axis, the y-axis, and the z-axis may beperpendicular to one another, or may represent different directions thatare not perpendicular to one another.

FIG. 1 is a perspective view of a display apparatus 1 according to anexemplary embodiment of the present invention.

Referring to FIG. 1, the display apparatus 1 includes a display area DAon which images are displayed and a non-display area NDA that does notdisplay images. The display apparatus 1 may provide a main image vialight emitted from a plurality of main pixels Pm arranged in the displayarea DA.

The display apparatus 1 includes a sensor area SA. The sensor area SAmay be an area where a component such as a sensor is configured todetect an input using an infrared ray, a visible ray, or sound. Thesensor area SA may include a transmission portion TA, through whichlight and/or sound output incident to or originating from the componentare transmitted to the outside. According to an exemplary embodiment ofthe present invention, when the light transmits through the sensor areaSA, a light transmittance may be about 10% or greater. For example, thelight transmittance through the sensor area SA may be 20% or greater,25% or greater, 50% or greater, 85% or greater, or 90% or greater.

According to an exemplary embodiment of the present invention, aplurality of auxiliary pixels Pa may be arranged in the sensor area SA,and a predetermined image may be provided by using light emitted fromthe plurality of auxiliary pixels Pa. The image provided from the sensorarea SA is an auxiliary image having a resolution less than that of animage provided by the main pixels Pm disposed in the display area DA. Inother words, the sensor area SA includes the transmission portion TA,through which the light and/or sound may transmit, and thus, the numberof auxiliary pixels Pa per unit area may be less than that of the mainpixels Pm per unit area in the display area DA.

The sensor area SA may be at least partially surrounded by the displayarea DA. For example, as shown in FIG. 1, the sensor area SA may beentirely surrounded by the display area DA and disposed therein.According to an exemplary embodiment of the present invention, thesensor area SA may be interspersed at regular intervals throughout thedisplay area DA. For example, sensor areas SA may have a staggeredarrangement with respect to portions of the display area DA, or may havean alternating arrangement therewith.

Hereinafter, according to an exemplary embodiment of the presentinvention, it is considered that the display apparatus 1 is an organiclight-emitting display apparatus, but the display apparatus 1 is notlimited thereto. For example, the display apparatus 1 may be aninorganic light-emitting display, a quantum dot light-emitting display,etc.

Referring to FIG. 1, the sensor area SA is in a portion (upper rightportion) of the display area DA of a rectangular shape, but the presentinvention is not limited thereto. For example, the display area DA mayhave a circular shape, an ellipse shape, or a polygonal shape such as atriangle, a pentagon, etc., and a location of the sensor area SA and thenumber of sensor areas SA may be variously modified.

FIG. 2 is a cross-sectional view of the display apparatus 1 according toan exemplary embodiment of the present invention. FIG. 2 shows across-section taken along line A-A′ of FIG. 1.

Referring to FIG. 2, the display apparatus 1 may include a display panel10 including display elements, and a component 20 located under thedisplay panel 10 to correspond to the sensor area SA. For example, thecomponent 20 may at least partially overlap the transmission area TA andthe organic light-emitting diode OLED in a thickness direction (e.g., aZ direction). However, the present invention is not limited thereto. Forexample, the component 20 may contact a side wall of an adjacent displayarea DA, and the organic light-emitting diode OLED of the main pixel Pmmay contact an outer boundary of the transmission area TA to increasespace efficiency and resolution.

The display panel 10 may include a substrate 100, a buffer layer 111, adisplay element layer 200 on the substrate 100, and a thin filmencapsulation layer 300 that is a sealing member for sealing the displayelement layer 200. In addition, the display panel 10 may further includea lower protective film 175 arranged under the substrate 100. Forexample, portions of the lower protective film 175 may be spaced apartfrom the component 20 in the first direction (e.g., an x direction) andmay correspond to the display area DA.

The substrate 100 may include glass and/or a polymer resin. The polymerresin may include polyethersulfone, polyacrylate, polyetherimide,polyethylene naphthalate, polyethylene terephthalate, polyphynylenesulfide, polyarylate, polyimide, polycarbonate and/or cellulose acetatepropionate. The substrate 100 including the polymer resin may beflexible, rollable, or bendable. The substrate 100 may have amulti-layered structure including a layer including the polymer resinand/or an inorganic layer.

The display element layer 200 may include a circuit layer including thinfilm transistors TFTm and TFTa, an organic light-emitting diode OLEDthat is a display element, and an insulating layer IL between thin filmtransistors TFT and TFT and the organic light-emitting diode OLED.

The main pixels Pm each including a main thin film transistor TFTm andan organic light-emitting diode OLED connected to the main thin filmtransistor TFT are arranged in the display area DA, and the auxiliarypixels Pa each including an auxiliary thin film transistor TFTa and anorganic light-emitting diode OLED connected to the auxiliary thin filmtransistor TFTa and wirings may be arranged in the sensor area SA.

In addition, the transmission portion TA, in which the auxiliary thinfilm transistor TFTa and display elements are not arranged, may belocated in the sensor area SA. The transmission portion TA may beunderstood as an area, through which light/signals emitted from thecomponent 20 and/or light/signals incident to the component 20 transmitoutwardly.

The component 20 may be located in the sensor area SA. The component 20may be an electronic element using light or sound. For example, thecomponent 20 may be a sensor for receiving light, e.g., an infrared raysensor, a sensor outputting and sensing light or sound to measure adistance or to sense fingerprints, etc., a small-sized lamp emittinglight, or a speaker outputting sound. The electronic element using lightmay use light of various wavelength bands such as visible light, IR,ultraviolet (UV) ray, etc. A plurality of components 20 may be arrangedin the sensor area SA. For example, a light-emitting device and alight-receiving device may be provided in one sensor area SA as thecomponents 20. Alternatively, one component 20 may include alight-emitting portion and a light-receiving portion.

According to an exemplary embodiment of the present invention, a layerBSM may refer to a conductive layer, a sound blocking layer, and/or alight blocking layer. For convenience of description, exemplaryembodiments will be described hereafter including a conductive layerBSM. The conductive layer BSM may be arranged in the sensor area SA. Theconductive layer BSM may correspond to the auxiliary pixels Pa in thesensor area SA. For example, the conductive layer BSM may be arrangedcorresponding to a lower portion of the auxiliary thin film transistorTFTa. The conductive layer BSM may prevent external light emitted fromthe component 20 from reaching the auxiliary pixel Pa including theauxiliary thin film transistor TFTa.

According to an exemplary embodiment of the present invention, aconstant voltage or a signal is applied to the conductive layer BSM toprevent damage to a pixel circuit due to an electrostatic discharge. Theconductive layer BSM may electrically contact the wiring that isconnected to the auxiliary pixel Pa to apply electric power or signalsthereto, so that a constant voltage or a signal may be applied to theconductive layer BSM. For example, the conductive layer BSM may receivea ground voltage or a predetermined voltage of the auxiliary pixel Pa.For example, the conductive layer BSM may receive a voltage or signalfrom a scan line or a driving voltage line, but the present invention isnot limited thereto.

The thin film encapsulation layer 300 may include at least one inorganicencapsulation layer and at least one organic encapsulation layer. Inthis regard, referring to FIG. 2, the thin film encapsulation layer 300may include first and second inorganic encapsulation layers 310 and 330,respectively, and an organic encapsulation layer 320 between the firstand second inorganic encapsulation layers 310 and 330.

The first and second inorganic encapsulation layers 310 and 330 mayinclude one or more inorganic insulating materials such as aluminumoxide, titanium oxide, tantalum oxide, hafnium oxide, zinc oxide,silicon oxide, silicon nitride, and/or silicon oxynitride. The organicencapsulation layer 320 may include a polymer-based material. Thepolymer-based material may include polyethylene terephthalate,polyethylene naphthalate, polycarbonate, polyimide, polyethylenesulfonate, polyoxymethylene, polyarylate, hexamethyl disiloxane and/oran acryl-based resin (e.g., polymethyl methacrylate, polyacrylic acid,etc.).

The lower protective film 175 is attached to a lower portion of thesubstrate 100 and may protect and support the substrate 100. The lowerprotective film 175 may include an opening 1750P corresponding to thesensor area SA. Since the lower protective film 175 includes the opening1750P, a light transmittance of the sensor area SA may be increased. Thelower protective film 175 may include polyethyelene terepthalate and/orpolyimide.

A width of the sensor area SA in the first direction (e.g., the xdirection) may be greater than a width of the component 20 in the firstdirection (e.g., the x direction). In FIG. 2, the width of the sensorarea SA is equal to the width of the opening 1750P, but the width of theopening 1750P in the lower protective film 175 may not be equal to thatof the sensor area SA. For example, the width of the opening 1750P maybe less than the width of the sensor area SA.

Components such as an input sensing member for sensing a touch input, ananti-reflection member including a polarizer and a retarder, or a colorfilter and a black matrix, a transparent window, etc. may be furtherarranged on the display panel 10.

The thin film encapsulation layer 300 may also be referred to herein asan encapsulation member 300 for sealing the display element layer 200.For example, an encapsulation substrate that is bonded to the substrate100 via a sealant or a frit may be used as the encapsulation member 300for the display element layer 200.

According to an exemplary embodiment of the present invention, thesensor area SA may include two auxiliary pixels Pa and a transmissionportion TA disposed between the two auxiliary pixels Pa, when viewed ina cross-sectional view.

According to an exemplary embodiment of the present invention, theauxiliary pixel Pa may be disposed between two transmission areas TA,when viewed in a cross-sectional view.

According to an exemplary embodiment of the present invention, thesensor areas SA may be disposed in rows and/or columns. In such anembodiment, the auxiliary pixel PA may be slightly larger relative to amain pixel Pm to reduce a size of a non-transmittance region of thesensor area SA. For example, the auxiliary pixel Pa may contact thetransmission area TA or may partially overlap the transmission area TA.The component(s) 20 may individually or collectively extend in thesecond direction (e.g., a y direction). The component(s) 20 may have awidth in the first direction (e.g., the x direction) that substantiallycorresponds to a width of the transmission area TA in the firstdirection (e.g., the x direction).

According to an exemplary embodiment of the present invention, thetransmission area TA may have an annular shape in a plane defined by thefirst direction (e.g., the x direction) and the second direction (e.g.,the y direction) with the auxiliary pixel Pa disposed at its center. Inthis embodiment, the component 20 may be annular or a solid circle shapeof substantially the same diameter as the transmission area TA andoverlapping therewith. The conductive layer BSM may have a circularshape with a smaller diameter than the transmission area TA and theconductive layer BSM.

According to an exemplary embodiment of the present invention, thecomponent 20 may be disposed as a layer on the substrate 100 below theauxiliary pixels Pm and the conductive layer BSM, and substantially allpixels of the display apparatus 1 may be auxiliary pixels Pa. In such acase, the transmission area TA may be disposed between adjacentauxiliary pixels Pa.

FIG. 3 is a plan view of the display panel 10 according to an exemplaryembodiment of the present invention, and FIG. 4 is a plan view showingan enlarged view of the sensor area SA of FIG. 3 according to anexemplary embodiment of the present invention.

Referring to FIG. 3, the display panel 10 is arranged in the displayarea DA and includes the plurality of main pixels Pm. Each of the mainpixels Pm may include a display element such as an organiclight-emitting diode OLED. Each of the main pixels Pm may emit light,e.g., red light, green light, blue light, or white light, via theorganic light-emitting diode OLED. The main pixel Pm may be understoodas a pixel emitting red light, green light, blue light, or white light,as described above. The display area DA is covered by the encapsulationmember 300 described above with reference to FIG. 2, so as to beprotected against external air or moisture.

The sensor area SA may be arranged in the display area DA and theplurality of auxiliary pixels Pa are arranged in the sensor area SA.Each of the auxiliary pixels Pa may include a display element such as anorganic light-emitting diode. Each of the auxiliary pixels Pa may emitlight, e.g., red light, green light, blue light, or white light, via theorganic light-emitting diode. The auxiliary pixel Pa may be understoodas a pixel emitting red light, green light, blue light, or white light,as described above. In addition, the sensor area SA includes thetransmission portion TA between adjacent auxiliary pixels Pa.

The sensor area SA includes the transmission portion TA, and thus aresolution of the sensor area SA may be less than that of the displayarea DA. For example, the resolution of the sensor area SA may be halfthe resolution of the remainder of the display area DA, According to anexemplary embodiment of the present invention, the resolution of thedisplay area DA may be 400 PPI or greater, and the resolution of thesensor area SA may be about 200 PPI or greater.

Referring to FIG. 4, the sensor area SA may include an auxiliary pixelarea PaA including at least one auxiliary pixel Pa, and a transmissionarea TAA including the transmission portion TA. The auxiliary pixel areaPaA and the transmission area TAA may be arranged in a grid shape.

According to an exemplary embodiment of the present invention, theauxiliary pixel area PaA may include a first auxiliary pixel Paremitting red light, a second auxiliary pixel Pag emitting green light,and a third auxiliary pixel Pab emitting blue light. FIG. 4 shows theauxiliary pixels Pa of a Pentile type, but the auxiliary pixels Pa maybe formed in a stripe pattern. Also, in FIG. 4, eight auxiliary pixelsPa are included in the auxiliary pixel area PaA, but the number ofauxiliary pixels Pa may vary depending on a resolution of the sensorarea SA.

According to an exemplary embodiment of the present invention, one mainpixel Pm and one auxiliary pixel Pa may include the same pixel circuits.However, the present invention is not limited thereto. In other words,the pixel circuit included in the main pixel Pm and the pixel circuitincluded in the auxiliary pixel Pa may be different from each other.

Referring to FIG. 3, each of the main and auxiliary pixels Pm and Pa maybe electrically connected to components arranged in the non-display areaNDA. For example. in the non-display area NDA, a first scan drivingcircuit 110, a second scan driving circuit 120, a terminal 140, a datadriving circuit 150, a first power supply line 160, and a second powersupply line 170 may be arranged.

The first scan driving circuit 110 may provide each pixel Pm or Pa witha scan signal via a scan line SL. The first scan driving circuit 110 mayprovide each pixel Pm or Pa with an emission control signal via anemission control line EL. The second scan driving circuit 120 may bearranged in parallel with the first scan driving circuit 110; with thedisplay area DA arranged therebetween. Some of the pixels Pm and Paarranged in the display area DA may be electrically connected to thefirst scan driving circuit 110, and the other pixels may be connected tothe second scan driving circuit 120. According to an exemplaryembodiment of the present invention, the second scan driving circuit 120may be omitted.

The terminal 140 may be arranged at a side of the substrate 100. Theterminal 140 may not be covered by an insulating layer but is exposed,and may be electrically connected to a printed circuit board PCB. Aterminal PCB-P of the printed circuit board PCB may be electricallyconnected to the terminal 140 of the display panel 10. The printedcircuit board PCB may transfer a signal or power of a controller to thedisplay panel 10. A control signal generated by the controller may berespectively transferred to the first and second scan driving circuits110 and 120 via the printed circuit board PCB. The controller mayprovide the first and second power supply lines 160 and 170 respectivelywith a first power voltage ELVDD and a second power voltage ELVSS (seeFIG. 5 and FIG. 6) via first and second connecting lines 161 and 171.The first power voltage ELVDD is supplied to each main pixel Pm orauxiliary pixel Pm via a driving voltage line PL connected to the firstpower supply line 160, and the second power voltage ELVSS may beprovided to an opposite electrode of each pixel Pm or Pa connected tothe second power supply line 170.

The data driving circuit 150 is electrically connected to a data line DLA data signal of the data driving circuit 150 may be provided to each ofthe pixels Pm and Pa via a connecting line 151 connected to the terminal140 and the data line DL connected to the connecting line 151. AlthoughFIG. 3 shows that the data driving circuit 150 is arranged on theprinted circuit board PCB, the data driving circuit 150 may be arrangedon the substrate 100 according to an exemplary embodiment of the presentinvention. For example, the data driving circuit 150 may be arrangedbetween the terminal 140 and the first power supply line 160.

The first power supply line 160 may include a first sub-line 162 and asecond sub-line 163 that extend in parallel with each other in the firstdirection (e.g., the X-direction) with the display area DA therebetween.The second power supply line 170 has a loop shape having an open side topartially surround the display area DA.

FIG. 5 is an equivalent circuit diagram of a pixel according to anexemplary embodiment of the present invention, and FIG. 6 is anequivalent circuit diagram of a pixel according to an exemplaryembodiment of the present invention.

The equivalent circuit diagram of FIG. 5 or FIG. 6 may be applied to themain pixel Pm and/or the auxiliary pixel Pa.

Referring to FIG. 5, each of the main and auxiliary pixels Pm and Pa mayinclude a pixel circuit PC connected to the scan line SL and the dataline DL and an organic light-emitting diode OLED connected to the pixelcircuit PC.

The pixel circuit PC includes a driving thin film transistor T1, aswitching thin film transistor T2, and a storage capacitor Cst. Theswitching thin film transistor T2 is connected to the scan line SL andthe data line DL and transfers a data signal Dm input through the dataline DL to the driving thin film transistor T1 according to a scansignal Sn input through the scan line SL.

The storage capacitor Cst is connected to the switching thin filmtransistor T2 and a driving voltage line PL and stores a voltagecorresponding to a difference between a voltage transferred from theswitching thin film transistor T2 and the first power voltage ELVDD (ordriving voltage) supplied to the driving voltage line PL.

The driving thin film transistor T1 is connected to the driving voltageline PL and the storage capacitor Cst and may control a driving currentflowing from the driving voltage line PL to the organic light-emittingdiode OLED in response to the voltage value stored in the storagecapacitor Cst. The organic light-emitting diode OLED may emit lighthaving a predetermined luminance according to the driving current.

FIG. 5 shows an example in which the pixel circuit PC includes two thinfilm transistors and one storage capacitor, but the present invention isnot limited thereto. As shown in FIG. 6, the pixel circuit PC mayinclude seven thin film transistors and one storage capacitor.

Referring to FIG. 6, each of the main and auxiliary pixels Pm and Paincludes a pixel circuit PC and an organic light-emitting diode OLEDconnected to the pixel circuit PC. The pixel circuit PC may include aplurality of thin film transistors and a storage capacitor. The thinfilm transistors and the storage capacitor may be connected to signallines SL, SL-1, EL, and DL, an initialization voltage line VL, and adriving voltage line PL.

In FIG. 6, each pixel Pm or Pa is connected to the signal lines SL,SL-1, EL, and DL, the initialization voltage line VL, and the drivingvoltage line PL, but one or more embodiments are not limited thereto. Asanother embodiment, at least one of the signal lines SL, SL-1, EL, andDL, the initialization voltage line VL, and the driving voltage line PLmay be shared by neighboring pixels P.

The plurality of thin film transistors may include a driving TFT T1, aswitching TFT T2, a compensation TFT T3, a first initialization TFT T4,an operation control TFT T5, an emission control TFT T6, and a secondinitialization TFT T7.

The signal lines include the scan line SL transferring a scan signal Sn,a previous scan line SL-1 transferring a previous scan signal Sn-1 tothe first initialization TFT T4 and the second initialization TFT T7, anemission control line EL transferring an emission control signal En tothe operation control TFT T5 and the emission control TFT T6, and a dataline DL intersecting with the scan line SL and transferring a datasignal Dm. The driving voltage line PL transfers the driving voltageELVDD to the driving TFT T1, and the initialization voltage line VLtransfers an initialization voltage Vint for initializing the drivingTFT T1 and the pixel electrode.

A driving gate electrode G1 of the driving TFT T1 is connected to afirst storage capacitor plate Cst1 of the storage capacitor Cst, adriving source electrode S1 of the driving TFT T1 is connected to thedriving voltage line PL via the operation control TFT T5, and a drivingdrain electrode D1 of the driving TFT T1 is electrically connected tothe pixel electrode of the organic light-emitting diode OLED via theemission control TFT T6. The driving TFT T1 receives the data signal Dmaccording to a switching operation of the switching TFT T2 to supply adriving current I_(OLED) to a main organic light-emitting diode OLED.

A switching gate electrode G2 of the switching TFT T2 is connected tothe scan line SL, a switching source electrode S2 of the switching TFTT2 is connected to the data line DL, a switching drain electrode D2 ofthe switching TFT T2 is connected to the driving source electrode S1 ofthe driving TFT T1 and at the same time, is connected to the drivingvoltage line PL via the operation control TFT T5. The switching TFT T2is turned on according to the scan signal Sn received through the scanline SL and performs a switching operation that transfers the datasignal Dm transferred through the data line DL to the driving sourceelectrode S1 of the driving TFT T1.

A compensation gate electrode G3 of the compensation TFT T3 is connectedto the scan line SL, a compensation source electrode S3 of thecompensation TFT T3 is connected to the driving drain electrode D1 ofthe driving TFT T1 and at the same time is connected to the pixelelectrode of the organic light-emitting diode OLED via the emissioncontrol TFT T6, and a compensation drain electrode D3 of thecompensation TFT T3 is connected to the first storage capacitor plateCst1 of the storage capacitor Cst, a first initialization drainelectrode D4 of the first initialization TFT T4, and the driving gateelectrode G1 of the driving TFT T1. The compensation TFT T3 is turned onaccording to the scan signal Sn received through the scan line SL toelectrically connect the driving gate electrode G1 and the driving drainelectrode D1 of the driving TFT T1 to each other and to diode-connectthe driving TFT T1.

A first initialization gate electrode G4 of the first initialization TFTT4 is connected to the previous scan line SL-1, a first initializationsource electrode S4 of the first initialization TFT T4 is connected to asecond initialization drain electrode D7 of the second initializationTFT T7 and the initialization voltage line VL, and the firstinitialization drain electrode D4 of the first initialization TFT T4 isconnected to the first storage capacitor plate Cst1 of the storagecapacitor Cst, the compensation drain electrode D3 of the compensationTFT T3, and the driving gate electrode G1 of the driving TFT T1. Thefirst initialization TFT T4 is turned on according to a previous scansignal Sn-1 transferred through the previous scan line SL-1 to transferthe initialization voltage Vint to the driving gate electrode G1 of thedriving TFT T1 and perform an initialization operation for initializinga voltage at the driving gate electrode G1 of the driving TFT T1.

An operation control gate electrode G5 of the operation control TFT T5is connected to the emission control line EL, an operation controlsource electrode S5 of the operation control TFT T5 is connected to thedriving voltage line PL, and an operation control drain electrode D5 ofthe operation control TFT T5 is connected to the driving sourceelectrode S1 of the driving TFT T1 and the switching drain electrode D2of the switching TFT T2.

An emission control gate electrode G6 of the emission control TFT T6 isconnected to the emission control line EL, an emission control sourceelectrode S6 of the emission control TFT T6 is connected to the drivingdrain electrode D1 of the driving TFT T1 and the compensation sourceelectrode S3 of the compensation TFT T3, and an emission control drainelectrode D6 of the emission control TFT T6 is electrically connected toa second initialization source electrode S7 of the second initializationTFT T7 and the pixel electrode of the organic light-emitting diode OLED.

The operation control TFT T5 and the emission control TFT T6 aresimultaneously turned on according to the emission control signal Entransferred through the emission control line EL to transfer the drivingvoltage ELVDD to the main organic light-emitting diode OLED and to allowa driving current I_(OLED) to flow in the organic light-emitting diodeOLED.

The second initialization gate electrode G7 of the second initializationTFT T7 is connected to the previous scan line SL-1, a secondinitialization source electrode S7 of the second initialization TFT T7is connected to the emission control drain electrode D6 of the emissioncontrol TFT T6 and the pixel electrode of the main organiclight-emitting diode OLED, and a second initialization drain electrodeD7 of the second initialization TFT T7 is connected to the firstinitialization source electrode S4 of the first initialization TFT T4and the initialization voltage line VL. The second initialization TFT T7is turned on according to the previous scan signal Sn-1 transferredthrough the previous scan line SL-1 to initialize the pixel electrode ofthe main organic light-emitting diode OLED.

In FIG. 6, the first initialization TFT T4 and the second initializationTFT T7 are connected to the previous scan line SL-1, but the a pixelcircuit according to the present invention is not limited thereto.According to an exemplary embodiment of the present invention, the firstinitialization TFT 14 may be connected to the previous scan line SL-1 tooperate according to the previous scan signal Sn-1, and the secondinitialization TFT 17 may be connected to a separate signal line (e.g.,a post scan line) to operate according to a signal transferred to thesignal line.

A second storage capacitor plate Cst2 of the storage capacitor Cst isconnected to the driving voltage line PL, and an opposite electrode ofthe organic light-emitting diode OLED is connected to the common voltage(i.e., second power voltage) ELVSS. Accordingly, the organiclight-emitting diode OLED emits light by receiving the driving currentI_(OLED) from the driving TFT T1 to display images.

In FIG. 6, the compensation TFT T3 and the first initialization TFT T4have dual-gate electrodes, but the compensation TFT T3 and the firstinitialization TFT T4 may each have one gate electrode.

According to an exemplary embodiment of the present invention, the mainpixel Pm and the auxiliary pixel Pa may include same pixel circuits PC.However, the present invention is not limited thereto. The main pixel Pmand the auxiliary pixel Pa may have pixel circuits PC having differentstructures from each other. For example, the main pixel Pm may adopt thepixel circuit shown in FIG. 6, and the auxiliary pixel Pa may adopt thepixel circuit shown in FIG. 5.

FIG. 7 is a cross-sectional view showing a display panel according to anexemplary embodiment of the present invention. FIG. 7 is across-sectional view of an auxiliary pixel Pa of a sensor area SA.

The auxiliary pixels Pa and the transmission portion TA may be locatedin the sensor area SA. Hereinafter, one pixel structure will bedescribed based on the auxiliary pixel Pa, but the same structure may bealso applied to the main pixel Pm.

The substrate 100 may include glass and/or a polymer resin. The polymerresin may include a polyethersulfone, polyacrylate, polyetherimide,polyethylene naphthalate, polyethylene terephthalate, polyphynylenesulfide, polyarylate, polyimide, polycarbonate, cellulose acetatepropionate, etc. The substrate 100 including the polymer resin may beflexible, rollable, or bendable. The substrate 100 may have amulti-layered structure including a layer including the polymer resinand an inorganic layer.

A buffer layer 111 and a barrier layer 101 are located on the substrate100 to reduce or block infiltration of impurities, moisture, or externalair from a lower portion of the substrate 100, and to provide a flatsurface on the substrate 100. The buffer layer 111 and the barrier layer101 may include an inorganic material such as an oxide material, anitride material, an organic material, and/or an inorganic-organiccomposite material, and may have a single-layered or multi-layeredstructure including the inorganic material and the organic material.Referring to FIGS. 7 to 15, the conductive layer BSM may be arrangedbetween the barrier layer 101 and the buffer layer 111. In an exemplaryembodiment of the present invention, the buffer layer 111 may be omittedand the conductive layer BSM may be arranged on the substrate 100directly.

Auxiliary thin film transistors TFTa1 and TFTa2 may be arranged on thebuffer layer 111. In FIG. 7, the auxiliary pixel Pa includes twoauxiliary thin film transistors TFTa1 and TFTa2, but may include threeor more auxiliary thin film transistors.

A semiconductor layer A may be arranged on the buffer layer 111. Thesemiconductor layer A may include, for example, amorphous silicon.According to an exemplary embodiment of the present invention, thesemiconductor layer A may include an oxide semiconductor includingindium (In), gallium (Ga), stannum (Sn), zirconium (Zr), vanadium (V),hafnium (Hf), cadmium (Cd), germanium (Ge), chrome (Cr), titanium (Ti),and/or zinc (Zn). For example, the semiconductor layer A may include anoxide semiconductor such as indium gallium zinc oxide (IGZO), zinc tinoxide (ZTO), and/or zinc indium oxide (ZIO).

The gate electrode G is arranged on the semiconductor layer A with agate insulating layer 113 therebetween. The gate electrode G may includemolybdenum (Mo), aluminum (Al), copper (Cu), and/or titanium (Ti), andmay have a single-layered or multi-layered structure. As an example, thegate electrode G may include a single layer including Mo.

The gate insulating layer 113 may include an insulating material such assilicon oxide (SiO₂), silicon nitride (SiNx), silicon oxynitride (SiON),aluminum oxide (Al₂O₃), titanium oxide (TiO₂), tantalum oxide (Ta₂O₅),hafnium oxide (HfO₂), and/or zinc oxide (ZnO₂).

A source electrode S and/or a drain electrode D are arranged on the gateelectrode G with an interlayer insulating layer 115 therebetween. Thesource electrode S and/or the drain electrode D include Mo, Al, Cu,and/or T1, and may each have a single-layered or a multi-layeredstructure. For example, the source electrode S and/or the drainelectrode D may each have a multi-layered structure including Ti/Al/Ti.

The planarization layer 117 covers an upper surface of the sourceelectrode S and/or the drain electrode D, and may have a flat uppersurface for planarizing a pixel electrode 210. The planarization layer117 may include a single-layered or multi-layered structure including anorganic material. The planarization layer 117 may includebenzocyclobutene (BCB), polyimide, hexamethyldisiloxane (HMDSO),polymethylmethacrylate (PMMA), polystyrene (PS), polymer derivativeshaving phenol groups, an acryl-based polymer, an imide-based polymer, anaryl ether-based polymer, an amide-based polymer, a fluoride-basedpolymer, a p-xylene-based polymer, and/or a vinyl alcohol-based polymer.The planarization layer 117 may include an inorganic material. Theplanarization layer 117 may include an insulating material such assilicon oxide (SiO₂), silicon nitride (SiNx), silicon oxynitride (SiON),aluminum oxide (Al₂O₃), titanium oxide (TiO₂), tantalum oxide (Ta₂O₅),hafnium oxide (HfO₂), and zinc oxide (ZnO₂). When the planarizationlayer 117 includes the inorganic material, chemical planarizationpolishing may be performed if necessary. Alternatively, theplanarization layer 117 may include both an organic material and aninorganic material.

The pixel electrode 210 may include a semi-transmissive electrode or areflective electrode. According to an exemplary embodiment of thepresent invention, the pixel electrode 210 may include a reflectivelayer including Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, and/or Cr, and atransparent or semi-transparent electrode layer on the reflective layer.The transparent or semi-transparent electrode layer may include indiumtin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium oxide(In₂O₃), indium gallium oxide (IGZO), and aluminum zinc oxide (AZO).According to an exemplary embodiment of the present invention, the pixelelectrode 210 may include a stack structure including ITO/Ag/ITO.

A pixel defining layer 119 may be located on the planarization layer117, and the pixel defining layer 119 includes an opening exposing acenter portion of the pixel electrode 210 to define a light emittingregion of the pixel. Also, the pixel defining layer 119 increases adistance between an edge of the pixel electrode 210 and an oppositeelectrode 230 on the pixel electrode 210 to prevent generation of arc atthe edge of the pixel electrode 210. The pixel defining layer 119 mayinclude an organic insulating material such as polyimide, polyamide, anacrylic resin, BCB, HMDSO, and/or a phenol resin, and may be formed by aprocess such as spin coating.

The intermediate layer 220 of the organic light-emitting diode OLED mayinclude an organic light-emitting layer. The organic light-emittinglayer may include an organic material including a fluorescent orphosphor material emitting red, green, blue, or white light. The organiclight-emitting layer may include a low-molecular weight organic materialand/or a polymer organic material, and functional layers such as a holetransport layer (HTL), a hole injection layer (HIL), an electrontransport layer (ETL), and an electron injection layer (EIL) may beselectively arranged under and on the organic light-emitting layer. Theintermediate layer 220 may correspond to each of the plurality of pixelelectrodes 210. However, exemplary embodiments of the present inventionare not limited thereto. The intermediate layer 220 may be variouslymodified. In other words, the intermediate layer 220 may be arrangedthroughout the plurality of pixel electrodes 210.

The opposite electrode 230 may include a transmissive electrode or areflective electrode. According to an exemplary embodiment of thepresent invention, the opposite electrode 230 may include a transparentor a semi-transparent electrode, and may be provided as a metal thinfilm including Li, Ca, LiF/Ca, LiF/Al, Al, Ag, and/or Mg. Also, atransparent conductive oxide (TCO) such as ITO, IZO, ZnO, and/or In₂O₃may be further provided over the metal thin film. The opposite electrode230 is arranged throughout the display area DA and a peripheral area PA,and on the intermediate layer 220 and the pixel defining layer 119. Theopposite electrode 230 may be provided integrally with respect to theplurality of organic light-emitting diodes OLED to correspond to theplurality of pixel electrodes 210.

When the pixel electrode 210 is a reflective electrode and the oppositeelectrode 230 is a transmissive electrode, light emitted from theintermediate layer 220 is emitted towards the opposite electrode 230 andthe display apparatus is a top emission type. When the pixel electrode210 is a transparent or a semi-transparent electrode and the oppositeelectrode 230 is a reflective electrode, the light emitted from theintermediate layer 220 is discharged towards the substrate 100 and thedisplay apparatus may be a bottom emission type. However, exemplaryembodiments of the present invention are not limited thereto. Thedisplay apparatus according to an exemplary embodiment of the presentinvention may be a dual-emission type in which light is emitted to thetop and bottom surfaces thereof.

The above pixel structure may be applied to both the main pixel Pm andthe auxiliary pixel Pa.

In addition, the conductive layer BSM may be arranged under theauxiliary pixel Pa. The conductive layer BSM may be arranged between thesemiconductor layer A of the auxiliary thin film transistor TFTa and thesubstrate 100. The conductive layer BSM may overlap an entire lowersurface of the auxiliary pixel Pa, or may be patterned to overlap thesemiconductor layer A of the auxiliary thin film transistor TFTa. Theconductive layer BSM may prevent external light emitted from thecomponent 20 from reaching the auxiliary pixel Pa. For example, an upperstep of the conductive layer BSM may overlap the auxiliary thin filmtransistors TFTa1 and TFTa2 in a thickness direction (e.g., the Zdirection).

In addition, a predetermined constant voltage or a signal may be appliedto the conductive layer BSM. This will be described in detail below withreference to FIGS. 12 and 13.

The conductive layer BSM may be provided to have two or more steps at anedge thereof. The steps of the conductive layer BSM may be formed as astair shape. As such, the edge of the conductive layer BSM may have asmaller thickness than that of a center portion of the conductive layerBSM. According to an exemplary embodiment of the present invention, theconductive layer BSM may have a lower step that extends beyond a trenchdefined by the pixel defining layer 119 and the upper step of theconductive layer BSM may correspond to a width of the pixel electrode210 of the light emitting region of the organic light-emitting diodeOLE©.

According to an exemplary embodiment of the present invention, theconductive layer BSM has to have a predetermined thickness or greater inorder to block the light emitted from the component 20 (see FIG. 2). Inan experimental example, when light having a wavelength of 940 nm wasirradiated to a conductive layer BSM including Mo, a light transmittancewas about 8% in a case where the thickness of the conductive layer BSMis about 300 Å, about 3% in a case where the thickness of the conductivelayer BSM was about 500 Å, about 1% in a case where the thickness of theconductive layer BSM was about 800 Å, and 0% in a case where thethickness of the conductive layer BSM was about 1500 Å or greater. Thus,the conductive layer BSM is to have a thickness of about 1500 Å orgreater in order to completely block the light emitted from thecomponent 20.

However, in another experimental example, when the conductive layer BSMhad a thickness of about 800 Å or greater, cracks occurred in theinorganic layer and the semiconductor layer A of the auxiliary thin filmtransistor TFTa1 on the conductive layer BSM due to the step, anddefects such as disconnection occurred.

Thus, in the display panel 10 according to an exemplary embodiment ofthe present invention, the conductive layer BSM having two or more stepsat the edge thereof greatly reduces the occurrence of cracks anddisconnection defects. This will be described in detail below withreference to FIGS. 8 to 11.

FIGS. 8 to 11 are cross-sectional views showing display panels includingthe conductive layer BSM according to exemplary embodiments of thepresent invention. Referring to FIG. 8, the conductive layer BSM may bebetween the substrate 100 and the buffer layer 111. According to anexemplary embodiment of the present invention, an organic layer or aninorganic layer in addition to the buffer layer 111 may be furtherarranged on the conductive layer BSM. As shown in FIG. 7, thesemiconductor layer A of the thin film transistor may be arranged on thebuffer layer 111.

The conductive layer BSM may include aluminum (Al), platinum (Pt),palladium (Pd), silver (Ag), magnesium (Mg), glass, manganese (Mn), gold(Au), nickel (Ni), neodymium (Nd), iridium (Ir), chrome (Cr), lithium(Li), calcium (Ca), molybdenum (Mo), titanium (T1), tungsten (W), and/orcopper (Cu). The conductive layer BSM may have a single-layered or amulti-layered structure including the above-stated materials. Accordingto an exemplary embodiment of the present invention, the conductivelayer BSM may include a Mo layer. According to an exemplary embodimentof the present invention, when the component 20 is an infrared sensor,an area defined between upper steps of the conductive layer BSM(corresponding to thickness T12) may include a material that absorbsexternal visible light, and an area defined between lower steps of theconductive layer BSM (corresponding to thickness T11) may include aninfrared absorbent material.

A thickness T1 of the conductive layer BSM may be about 800 Å orgreater, for example, about 1500 Å or greater. According to an exemplaryembodiment of the present invention, the thickness T1 of the conductivelayer BSM may be about 2000 Å or greater, about 2500 Å or greater, about3000 Å or greater, about 3500 Å or greater, about 4000 Å or greater, orabout 5000 Å or greater.

The conductive layer BSM may have two or more steps at an edge portion Bthereof. The conductive layer BSM has two or more steps in order toallow the conductive layer BSM to have a thickness of about 800 Å orgreater, e.g., 1500A or greater, and at the same time, to prevent cracksor disconnection in the inorganic layer and the semiconductor layer A ofthe auxiliary thin film transistor TFTa on the conductive layer BSM dueto the step between layers. Therefore, in an exemplary embodiment of thepresent invention, thicknesses T11 and T12 of respective steps in theconductive layer BSM may each be less than 800 Å. For example, when thethickness T1 of the conductive layer BSM is 1500 Å, the thickness T11and the thickness T12 of the steps may each be 750 Å.

Referring to FIG. 9, according to an exemplary embodiment of the presentinvention, the conductive layer BSM may include a first conductive layerBSM1 and a second conductive layer BSM2 that are distinguished by thesteps. The second conductive layer BSM2 may be on the first conductivelayer BSM1. According to an exemplary embodiment of the presentinvention, the first conductive layer BSM1 and the second conductivelayer BSM2 may have different conductive materials from each other. Itmay be appreciated that the first conductive layer BSM1 and the secondconductive layer BSM2 having different conductive materials from eachother include metal materials having different etch rates from eachother.

The first conductive layer BSM1 includes a first conductive material,and the second conductive layer BSM2 includes a second conductivematerial, Here, the second conductive material at an upper layer may bea metal material having a greater etch rate than that of the firstconductive material at a lower layer. The etch rate is a parameterindicated in a speed showing the amount of a film that may be removedfor a predetermined time period via a same etchant. The etch rate isdefined by Equation 1 below.

E/R=x/t (x: etched thickness, t: etching time, units: nm/min, nm/sec, orÅ/min, Å/sec)  [Equation 1]

To obtain the different etch rates of the conductive materials, thesecond conductive material at the second conductive layer BSM2 may havea Young's modulus that is less than that of the first conductive layerBSM1. Since a metal material having a small Young's modulus is likely tobe deformed, a metal material having a relatively greater Young's ratemay be selected as the first conductive layer BSM1 and a metal materialhaving a relatively smaller Young's modulus may be selected as thesecond conductive layer BSM2. According to an exemplary embodiment ofthe present invention, the Young's modulus increases in an order of Al,T1, Mo, and W, the first conductive layer BSM1 and the second conductivelayer BSM2 may be obtained by using a combination of the stated metalmaterials. For example, when the first conductive layer BSM1 includesMo, the second conductive layer BSM2 may include Al.

According to an exemplary embodiment of the present invention, theconductive layer BSM may be formed by a wet etching or a dry etchingprocess. According to an exemplary embodiment of the present invention,when dry etching is used, an appropriate mixed gas may be used takinginto account characteristics of the second conductive material in orderto increase the etch rate of the second conductive layer BSM2 at theupper layer. In this case, even when the metal material having arelatively greater Young's modulus is located at the lower layer, thestepped structure of the conductive layer BSM may be obtained byapplying an appropriate etch gas. For example, when SF₆ (80 sccm) isused as the etch gas, the first conductive layer BSM1 at the lower layerincludes T1, and the second conductive layer BSM2 at the upper layerincludes W, the stepped structure of the conductive layer BSM may beobtained because the etch rate of W is greater than that of T1.

According to an exemplary embodiment of the present invention, when thefirst conductive layer BSM1 includes T1, the second conductive layerBSM2 may include Al. In this case, a modified etch gas may be used ifnecessary.

Referring to FIG. 10, in the conductive layer BSM, a width of a thirdconductive layer BSM3 in the first direction (e.g., the x direction) maybe less than a width of the second conductive layer BSM2.

Referring to FIG. 10, the display panel of FIG. 10 may include theconductive layer BSM having three or more steps. The conductive layerBSM may be between the substrate 100 and the buffer layer 111, and thesemiconductor layer A of the thin film transistor may be on the bufferlayer 111 as shown in FIG. 7.

A thickness T1′ of the conductive layer BSM may be about 800 Å orgreater, for example, about 1500 Å or greater. According to an exemplaryembodiment of the present invention, the thickness T1′ of the conductivelayer BSM may be about 2000 Å or greater, about 2500 Å or greater, about3000 Å or greater, about 3500 Å or greater, about 4000 Å or greater, orabout 5000 Å or greater.

The conductive layer BSM may have three or more steps at an edge portionC thereof. The conductive layer BSM has three or more steps in order toallow the conductive layer BSM to have a thickness of about 800 Å orgreater, e.g., 1500A or greater, and at the same time, to prevent cracksor disconnection in the inorganic layer and the semiconductor layer ofthe auxiliary thin film transistor TFTa on the conductive layer BSM dueto the step between layers. Therefore, thicknesses T11′, T12′, and T13′of respective steps in the conductive layer BSM may each be less than800 Å. For example, when the thickness T1′ of the conductive layer BSMis 1500 Å, the thickness T11′, the thickness T12′, and the thicknessT13′ of the steps may each be 500 Å. However, the present invention isnot limited thereto. For example, the thicknesses T11′, T12′ and T13′may be unequal.

Referring to FIG. 11, according to an exemplary embodiment of thepresent invention, the conductive layer BSM may include the firstconductive layer BSM1, the second conductive layer BSM2, and the thirdconductive layer BSM3 that are distinguished by the steps. The secondconductive layer BSM2 may be on the first conductive layer BSM1, and thethird conductive layer BSM3 may be on the second conductive layer BSM2.

According to an exemplary embodiment of the present invention, the firstto third conductive layers BSM1, BSM2, and BSM3 may have differentconductive materials from one another. It may be appreciated that thefirst to third conductive layers BSM1, BSM2, and BSM3 having differentconductive materials from one another have metal materials havingdifferent etch rates from one another.

For example. the first conductive layer BSM1 includes a first conductivematerial, the second conductive layer BSM2 includes a second conductivematerial, and the third conductive layer BSM3 includes a thirdconductive material. Here, the third conductive material at an uppermostlayer may be a metal material having a greater etch rate than that ofthe second conductive material, and the second conductive material maybe a metal material having a greater etch rate than that of the firstconductive material. To obtain the different etch rates among theconductive materials, the Young's moduli of the conductive materialsincluded in the conductive layer BSM may be reduced in an order of thefirst conductive material, the second conductive material, and the thirdconductive material. According to an exemplary embodiment of the presentinvention, when the first conductive layer BSM1 includes Mo, the secondconductive layer BSM2 may include Ti and the third conductive layer BSM3may include Al.

Referring to FIGS. 10 and 11, in the conductive layer BSM, a width ofthe third conductive layer BSM3 in a first direction (e.g., the xdirection) may be less than a width of the second conductive layer BSM2in the first direction (e.g., the x direction), and the width of thesecond conductive layer BSM2 in the first direction (e.g., the xdirection) may be less than a width of the first conductive layer BSM1in the first direction (e.g., the x direction).

FIG. 12 is a cross-sectional view showing a display panel according toan exemplary embodiment of the present invention. FIG. 12 shows amodified example of FIG. 7.

Referring to FIG. 12, the conductive layer BSM may be arrangedoverlapping only some of the thin film transistors of the auxiliarypixel Pa. For example, in FIG. 12, the conductive layer BSM is onlyarranged under the first auxiliary thin film transistor TFTa1 of theauxiliary pixel Pa, and may not be arranged under the second auxiliarythin film transistor TFTa2.

According to an exemplary embodiment of the present invention, the firstauxiliary thin film transistor TFTa1 may be the driving thin filmtransistor T1 or the switching thin film transistor T2 of FIG. 4.According to an exemplary embodiment of the present invention, the firstauxiliary thin film transistor TFTa1 may be the driving thin filmtransistor T1, the switching thin film transistor T2, the compensationthin film transistor T3, the first initialization thin film transistorT4, the operation control thin film transistor T5, the emission controlthin film transistor T6, or the second initialization thin filmtransistor T7 of FIG. 5.

FIGS. 13 and 14 are cross-sectional views showing display panelsaccording to exemplary embodiments of the present invention.

FIGS. 13 and 14 show the main pixel Pm in the display area DA and theauxiliary pixel Pa in the sensor area SA. As described above, theconductive layer BSM may be under the auxiliary pixel Pa. The conductivelayer BSM may be under the main pixel Pm.

In addition, a constant voltage or a signal is applied to the conductivelayer BSM to prevent damage to a pixel circuit due to an electrostaticdischarge. As shown in FIG. 13 or FIG. 14, the conductive layer BSM mayelectrically contact the wiring that is connected to the auxiliary pixelPa to apply electric power or signals thereto, so that a constantvoltage or a signal may be applied to the conductive layer BSM.

Referring to FIG. 13, the conductive layer BSM may be electricallyconnected to the driving voltage line PL via a contact hole in thesensor area SA so that the constant voltage is applied thereto. Thedriving voltage line PL includes the same material as those of thesource electrode S and/or the drain electrode D of the auxiliary thinfilm transistor TFTa, but is not limited thereto.

According to an exemplary embodiment of the present invention, theconductive layer BSM may be electrically connected to the scan line SLvia the contact hole in the sensor area SA so that a signal is appliedthereto, as shown in FIG. 14. The scan line SL includes the samematerial as that of the gate electrode G of the auxiliary thin filmtransistor TFTa, but is not limited thereto.

In the drawings, according to an exemplary embodiment of the presentinvention, the conductive layer BSM may be electrically connected to adriving voltage connecting line extending to the non-display area NDAvia a contact hole defined in the non-display area NDA (see FIG. 3) onthe outside of the display area DA. According to an exemplary embodimentof the present invention, the conductive layer BSM may be electricallyconnected to a scan connecting line extending to the non-display areaNDA via the contact hole defined in the non-display area NDA so that asignal is applied thereto.

FIG. 15 is a cross-sectional view showing a display panel according toan exemplary embodiment of the present invention.

Referring to FIG. 15, the sensor area SA includes the transmissionportion TA. The planarization layer 117 may include a first transmissionopening 1170P, the pixel defining layer 119 may include a secondtransmission opening 1190P, and the opposite electrode 230 may include athird transmission opening 2300P to correspond to the transmissionportion TA. Accordingly, in the transmission portion TA, the bufferlayer 111, the gate insulating layer 113, and the interlayer insulatinglayer 115 may overlap the substrate 100 in the third direction (e.g.,the Z direction).

According to an exemplary embodiment of the present invention, theopposite electrode 230 may not include the third transmission opening2300P, but may be arranged on the transmission portion TA. However, inthis case, the transmittance of the transmission portion TA may degradedue to the opposite electrode 230 that is a metal layer, and thus, theopposite electrode 230 corresponding to the transmission portion TA maybe removed.

According to an exemplary embodiment of the present invention, inorganicinsulating layers, for example, the buffer layer 111, the gateinsulating layer 113, and the interlayer insulating layer 115, may beall removed to correspond to the transmission portion TA. As describedabove, the layers may be removed in a region corresponding to thetransmission portion TA to increase the transmittance of thetransmission portion TA.

In addition, in the transmission portion TA, organic layers of theintermediate layer 220 formed on the entire surface of the substrate100, e.g., a hole transport layer, a hole injection layer, an electrontransport layer, an electron injection layer, etc. may be furtherarranged between the interlayer insulating layer 115 and the oppositeelectrode 230. Also, the thin film encapsulation layer 300 or a sealingsubstrate described above with reference to FIG. 2 may be also arrangedon the opposite electrode 230.

According to the exemplary embodiments of the present invention, thedisplay apparatus provided herein has an expanded display area fordisplaying images on the sensor area.

Accordingly, the display apparatus has increased image quality whileperforming various functions may be provided.

It should be understood that embodiments described herein should beconsidered in a descriptive sense only and not for purposes oflimitation.

While exemplary embodiments have been described with reference to thefigures, it will be understood by those of ordinary skill in the artthat various changes in form and details may be made therein withoutdeparting from the spirit and scope of the present invention as definedby the following claims.

What is claimed is:
 1. A display panel, comprising: a substrate; adisplay element layer on the substrate, the display element layercomprising a dis play element electrically connected to a thin filmtransistor; a conductive layer between the substrate and the thin filmtransistor, the conductive layer having a stair shape.
 2. The displaypanel of claim 1, wherein the conductive layer has two or more steps atan edge thereof.
 3. The display panel of claim 1, wherein the conductivelayer has an upper surface, a lower surface, and a side surfaceconnecting the upper surface and the lower surface, the side surfacehaving a stair shape.
 4. The display panel of claim 1, wherein theconductive layer has a thickness of 1500 Å or greater.
 5. The displaypanel of claim 2, wherein a height of one step among the steps of theconductive layer is less than 800 Å.
 6. The display panel of claim 1,wherein the conductive layer comprises a first conductive layer and asecond conductive layer on the first conductive layer, and the firstconductive layer and the second conductive layer include differentmaterials from each other.
 7. The display panel of claim 6, wherein thefirst conductive layer comprises a first conductive material and thesecond conductive layer comprises a second conductive material having anetch rate greater than an etch rate of the first conductive material. 8.The display panel of claim 6, wherein a width of the second conductivelayer in a first direction is less than a width of the first conductivelayer.
 9. The display panel of claim 1, wherein a thickness of an edgeof the conductive layer is less than a thickness of a center portion ofthe conductive layer.
 10. The display panel of claim 1, wherein thedisplay element layer further comprises: a scan line extending in afirst direction, the scan line for providing a scan signal to the secondpixels, and the conductive layer is electrically connected to the scanline via a contact hole.
 11. The display panel of claim 1, wherein thedisplay element layer further comprises: a driving voltage lineextending in a second direction, the driving voltage line for app lyinga driving voltage to the second pixels, and the conductive layer iselectrically connected to the driving voltage line via a contact hole.12. The display panel of claim 1, wherein the substrate comprises afirst area and a second area, the display element comprises a firstdisplay element electrically connected to a first thin film transistorin the first area and a second display element electrically connected toa second thin film transistor in the second area, the conductive layeroverlaps the second thin film transistor.
 13. The display panel of claim12, wherein an image provided on the second area has a resolution thatis less than a resolution of an image provided on the first area. 14.The display panel of claim 12, wherein the second area comprises anauxiliary pixel area and a transmission area, the auxiliary pixel areahaving at least one of the second pixels and the transmission areacomprising the transmission portion, and the auxiliary pixel area andthe transmission area are arranged in a grid shape.
 15. The displaypanel of claim 14, wherein the at least one second pixel comp rises apixel electrode, a common electrode, and an intermediate layer, thecommon electrode facing the pixel electrode and the intermediate layerbeing arranged between the pixel electrode and the common electrode, andthe common electrode comprises an opening corresponding to thetransmission area.
 16. A display apparatus, comprising: a substrate; adisplay element layer on the substrate, the display element layercomprising a dis play element electrically connected to a thin filmtransistor; a conductive layer between the substrate and the thin filmtransistor, the conductive layer having a stair shape; and a componentarranged under the substrate.
 17. The display apparatus of claim 16,wherein the component comprises an electronic element for emitting orreceiving light.
 18. The display apparatus of claim 16, wherein thedisplay element layer further comprises: a scan line and a drivingvoltage line, the scan line extending in a first direction and forproviding a scan signal to the display element and the driving voltageline extending in a second direction that intersects with the firstdirection and for applying a driving voltage to the display element, andthe conductive layer is electrically connected to the scan line or thedriving voltage line via a contact hole.
 19. The display apparatus ofclaim 16, wherein the conductive layer has a thickness of 1500 Å orgreater.
 20. The display apparatus of claim 16, wherein the stair shapeincludes two or more steps, and the two or more steps in the conductivelayer each have a thickness less than 800 Å.
 21. The display apparatusof claim 16, wherein the conductive layer comprises a first conductivelayer and a second conductive layer on the first conductive layer, andthe first conductive layer and the second conductive layer includedifferent materials from each other.
 22. The display apparatus of claim21, wherein the first conductive layer comprises a first conductivematerial and the second conductive layer comprises a second conductivematerial having an etch rate greater than an etch rate of the firstconductive material.
 23. The display apparatus of claim 16, wherein thesubstrate comprises a first area and a second area, the display elementcomprises a first display element electrically connected to a first thinfilm transistor in the first area and a second display elementelectrically connected to a second thin film transistor in the secondarea, the conductive layer overlaps the second thin film transistor. 24.The display apparatus of claim 23, wherein an image provided on thesecond area has a resolution that is less than a resolution of an imageprovided on the first area.
 25. The display apparatus of claim 23,wherein the second area is a sensor area.